After I updated the Thunderbold firmware to the newest one, all issues are gone.
I also had problems with the HDMI and Display port which I did not mention before. Sometimes the HDMI or Display-Port just stopped working after some random time but this is also gone after the update
I was not able to update the firmware via POP_OS! and installed it via WIndows. According to Foxtrek_64 you can also install it via linux:
